Assay-furnace.



' E. TENNENT.

ASSAY FURNACE.

APPLICATION FILED AUG. 22. 1908.

944,470. I Patented Dec. 28, 1909.

BSHBETS-SHEET 1.

B. E. TENNENT.

ASSAY FURNACE.

APPLICATION FILED AUG. 22, 1908.

944,470. Patented De0.28, 1909.

3 SHEETS-SHEET 2.

B. E. TBNNENT.

ASSAY FURNACE.

APPLICATION FILED we. 22.1908.

Patented Dec. 28,1909.

- BRUCE EDWARD TENNENT, OF KNIGHTS, TRANSVAAL.

ASSAY-FURNACE.

Appiication fi1ed. August 22, 1908. Serial No. 449,798.

T all whom it may concern:

Be it known that I, BRUCE EDWARD TEN- NENT, a subject of the King ofGreat Britain, and resident of Knights, Transvaal, have invented certainnew and useful Improvements in Assay- Furnaces, of which the followingis a specification.

This invention relates to assay-furnaces and in particular to a fusionor crucible furnace.

With the object of reducing the working costs, the furnace is moreparticularly designed for burning coal, although any other suitable fuelmay be used. In addition to effecting a very considerable reduction inthe cost. of fuel, the initial cost of a furnace constructed inaccordance with my invention is less than that of existing furnaces andthe life of the crucibles is considerably prolonged.

The firstly, in the employment of easily removable and renewable bars offirebrick or other suitably refractory material (which are preferablyarranged in two or more tiers) for supporting the crucibles within thefurnace in such a way that the flames and heated gases come directlyinto contact with the crucibles; and secondly, in providing in theash-pit of the furnace a rack or its equivalent for annealing orpreheating and cooling the crucibles before placing them in or afterwithdrawing them from the furnace. The more important advantagesaccruing to the first feature are (a) the economy effected in the fuelrequired for heating the furnace and the saving of time necessary forfusing the charges in the crucibles, and (b) the greater accuracy in theassays resulting from the even distribution of the heat throughout allthe crucibles in the chamber. The advantage accruing 'to the secondfeature is that by utilizing the waste heat of the ashpit to anneal orpreheat the crucibles before lacing them in the furnace and to graduallycool them after removal from the furnace, I obviate the frequentbreakages due to the sudden heating and cooling.

The invention will now be more fully described by aid of theaccompanying drawings in which, 1

Figure l is an elevation, partly in section, of the furnace, the planeof section being indicated by the line wm in Fig. 2. Fig. 2 is asectional plan, the plane of section being indicated by the line yy,Fig. 1, and Fig.

Specification of Letters Patent.

features of my invention consist,

Patented Dec. 28, 1909.

3 is a sectional elevation of Fig. 1 on th line 2-2. V

1 represents the brickwork of the furnace which is bound andstrengthened by means of buck-stays 2 (shown of channel section), tierods 3 and crosspieces 4. The stays and tie rods, as shown, are providedvertically and horizontally of the structure.

1 represent bars for supporting portions of the brickwork.

, 5 represents the bars of the firegrate of the furnace'and 6-thebearers therefor supporting the same at or in proximity to theirextremities.

7 is the firing door of the furnace and 8 the ashpit.

9 is that portion of the furnace in which the supports for the cruciblesare arranged. The supports consist of easily removable bars 10 offirebrick or other suitable refractory material. In the arrangementillustrated the bars 10 are arranged in two tiers immediately above thefiregrate surface. The lower set of bars 10 at their inner ends areseated within recesses 1O formed in the internal walls of the furnaceand at their other ends rest upon a ledge or projection 11 formed on thefurnace wall. The upper set or tier of bars 10, which is arranged atright angles to the lower set, is in like manner positioned in recesses10 in the side walls of the furnace at their inner ends and rest on acorresponding ledge 11 at their other ends. 13 and 1 1 are the doors(hereinafter designated the working doors of the furnace) for closingthe apertures 15, 16, through which access is obtained to insert orremove the crucibles. The apertures 15, 16, are shown at right angles,although they may be otherwise arranged. The working doors 13, 1 1, andalso the firing door 7 are shown provided at the bottom with rollers 17,which traverse an angleiron 18 fixed in the brickwork of the furnace, acorresponding angleiron 19 being fixed in the furnace to serve as aguide for the top of the door.

19 represents vertical boltsbetween the ends of the anglcirons 18, 19,serving as stops for limiting the movement of the door.

By this construction the several doors are opened laterally, whichermits the furnace to be worked with the oor only partially opened.

20 is the stack or chimney of the furnace and 21 the uptake leading fromthe top of the crucible chamber 9 to the stack. The

stack 20 is preferably fitted With a lid damper 22 actuated throughlever '23 and chain or equivalent 24 for regulating the draft throughthe furnace or for closin'g it A fireclay or other suitable,

when desired. pipe 25 may, if desired, be used as a lining for the lowerportion of the smoke stack 20.

In the ashpit 8 of the furnace is provided a rack 26, shown comprising apluralityof fixed parallel rods, for annealing the cruci supportedinrecesses and opposing'ledges in the Walls of the furnace, an aperturefor each set or tier, said apertures being ar ran ed at ri ht an lesWVOFklII doors for 21 22 b 7 in closing said apertures, said doors beingpro vided wlth rollers and the furnace w th guides to permit of the doorbelng opened horizontally, stops for limiting the move ment of the doorin either direction, and a rack in the ashpit of the furnace forgraduall heating and cooling the crucibles bythe aste heat, as setforth. V p

In testimony whereof I have s gned my name to this specification in thepresence of two subscribing witnesses.

BRUCE EDlVARD TENNENT.

Witnesses:

' GH s- QVENDALE;

R- QVENPALE-

